Bathroom and Trim Paint

I'm working on painting a bathroom, living room, and bedroom. The bathroom is pretty small and tiled half way up all the walls, so it does not require much paint to refresh it. It is just a little too big to cover with a quart and way too small for a gallon, and two quarts costs the same as a gallon. I'm also tired of the growing shelf of partial paint cans in my basement.

Since I am thinking of using a similar off-white/almond color for the trim in other rooms, I'm thinking I just buy a gallon and use the same paint for the bathroom walls plus the trim in the living room, hallway and bedroom.

I really don't have a mold problem in the bathroom. A little bit appears from time to time right above the shower, but that probably has more to do with the birds nest that was in the fan exhaust duct and my less than robust cleaning schedule. I believe the paint is BM Kitchen/Bath and about six years old.

Should I go with a good quality satin paint and not worry about "bathroom" designation? Add a mildewcide to the satin for the portion used in the bathroom? Just use Kitchen & Bath paint on the trim? Does it really matter?

I'm not doing a radical color change (cream to almond) and don't have any other issues, so was not planning on priming - except for the interior doors that I will be taking from stained to painted and will be the same paint as the trim.